Engine Block-Inspection - Jeep cherokee 1989 Owner's Manual

On V6 engines. remove the rear
camshaft cover plate (arrow)
surfaces with a light, rust preventive oil. If you have access to com-
pressed air, use it to speed the drying process and to blow out all the
oil holes and galleries. Warning: Wear eye protection when using com-
pressed air!
7 If the block isn't extremely dirty or sludged up, you can do an ade-
quate cleaning job with hot soapy water and a stiff brush. Take plenty
of time and do a thorough job. Regardless of the cleaning method used,
be sure to clean all oil holes and galleries very thoroughly, dry the block
completely and coat all machined surfaces with light oil.
8 The threaded holes in the block must be clean t o ensure accurate
torque readings during reassembly. Run the proper size tap into each
of the holes to remove rust, corrosion, thread sealant or sludge and
restore damaged threads (see illustration). If possible, use compressed
air to clear the holes of debris produced by this operation. Now is a
good time to clean the threads on the head bolts and the main bearing
cap bolts as well.
9 Reinstall the main bearing caps and tighten the bolts finger tight.
1 0 After coating the sealing surfaces of the new core plugs with Per-
Make sure they're driven in straight and seated properly or leakage
could result. Special tools are available for this purpose, but a large
socket, with an outside diameter that will just slip into the core plug,
a 112-inch drive extension and a hammer will work just as well.
1 1 Apply non-hardening sealant (such as Permatex no. 2 or Teflon
pipe sealant) to the new oil gallery plugs and thread them into the holes
in the block. Make sure they're tightened securely.
12 If the engine isn't going to be reassembled right away, cover
with a large plastic trash bag to keep it clean.
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1 5 Engine block inspection
Refer t o illustrations 75.4a, 15.46,
and 15.14d
1 Before the block is inspected, it should be cleaned as described
in Section 14.
2 Visually check the block for cracks, rust and corrosion. Look for
stripped threads in the threaded holes. It's also a good idea to have
the block checked for hidden cracks by an automotive machine shop
that has the special equipment to do this type of work. If defects are
found, have the block repaired, if possible, or replaced.
3
Check the cylinder bores for scuffing and scoring.
4 Measure the diameter of each cylinder at the top (just under the
ridge area), center and bottom of the cylinder bore, parallel to the
crankshaft axis (see illustrations).
The Motor Manual Guy
'Chapter 2 Part D General engine overhaul procedures
14.8 All bolt holes in the block
particularly the main bearing cap and
head bolt holes
and restored with a tap (be sure t o
remove debris from the holes after
-
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should be cleaned
this is done)
Measure the diameter of each cylinder just under
the wear ridge (A), at the center (B) and at the bottom (C)
it
The ability to "feel" when the telescoping gauge is
at the correct point will be developed over time, so work
slowly and repeat the check until you are satisfied that the
bore measurement is accurate
14.10 A large socket on an extension
can be used to drive the new soft plugs
into the bores